Electromagnetic touch control was once widely used in early panel-type devices due to its high positioning accuracy and high sensitivity to pressure. However, it has been gradually substituted by currently-prevalent multi-point capacitive touch control because it requires specialized electromagnetic stylus and thus is inconvenient for interaction between a user and the device.
With the wide application of touch control, people are realizing convenience of finger touch control and multi-point touch control. Particularly, the development of mobile phone and tablet computer encourages further exploration of new technology.
Multi-point capacitive touch control screen is the most popular one among various multi-point touch control technologies that are currently used. However, it has certain disadvantages. First, it has to be placed in front of a display screen, which may degrade display effect thereof. The degradation is especially significant for reflective screens. As a result, it can hardly be used in a paper-like display screen such as an electronic-ink screen. Secondly, the touch control object has to be conductive and have a relatively large area to enable the touch control. The user's finger can be used as the touch control object. However, it becomes non-conductive after wearing a glove and thus becomes ineffective as the touch control object. Also, accuracy and sensitivity of the touch control are susceptible to dirt and sweat on the finger. The interaction performance of the multi-point capacitive touch control screen is substantially compromised by these disadvantages. Contrary to the multi-point capacitive touch control screen, the electromagnetic touch control screen is typically arranged at the back side of the display screen and thus is very suitable for the reflective screens such as the electronic ink screen.
As described above, the multi-point capacitive touch control screen and the electromagnetic touch control screen both have certain disadvantages. The multi-point capacitive touch control screen has to be operated by the finger while the electromagnetic touch control screen has to be operated by the electromagnetic stylus. Neither of them can be conveniently operated by an arbitrary object.